1. Field of the Invention
The present invention relates to a photoconductive switch module, which is realized by a combination of light-emitting elements and photoconductive switch elements, and more particularly to a small photoconductive switch module in which photoconductive switch elements are integrated.
2. Description of the Related Art
U.S. Pat. No. 6,407,401B1 discloses a small high-frequency/high-performance photoconductive relay. The photoconductive relay, which realizes a small high-frequency switch, includes a photoconductive switch element, whose resistance varies according to the intensity of incident light, and a light-emitting element, which emits light to illuminate the photoconductive switch element, the photoconductive switch element and the light-emitting element being closely positioned to face each other. This photoconductive relay provides a minimum unit of a switch that can take the on state and the off state.
The photoconductive switch element is an element which is important to realize a photoconductive relay (photoconductive switch), and an example of such an element is disclosed in, e.g., U.S. Pat. No. 6,252,221B1.
In order to realize a sophisticated switch module, photoconductive switch elements must be used to constitute a switch circuit.
The circuit must be designed in such a manner that the layout becomes very compact, i.e., the wiring becomes short in order to obtain the good performance in a high frequency. That is, the photoconductive switch elements must be arranged in close proximity to each other.